The Los Angeles Times said the independent political action committee, Winning Our Future, has gotten another infusion of cash from Las Vegas Sands Chief Executive Sheldon Adelson.
The attack ads depict Romney as as out of touch and Santorum as unaccomplished, the report said.
The ads are set to run on television and radio, and are designed to boost Gingrich's chances in Super Tuesday states March 6. The ads are scheduled to air in Ohio, Tennessee and Oklahoma, as well as Gingrich's home state of Georgia.
One of the TV ads uses apparent "man-on-the-street" interviews with working-class voters. Among others, its shows a woman who says Gingrich is "the only one who understands what we're going through today," pointing to high gas prices.
"Romney's not the type to pump his own gas," she says as the screen shows an image of Romney boarding a private plane.
The Times said it's unclear how much Winning Our Future is spending on the ads, but a person familiar with the donation said the super PAC recently received a donation from Adelson similar to the two $5 million contributions he and his wife made in January.
A super PAC's expenditures by law are not coordinated with a campaign.